Investigators looking into the death of a Russian hunter suspect the man was fatally shot when his dog stepped on the trigger of a rifle he was holding.

The victim, a 64-year-old man in the Saratov Oblast, was apparently shot in the torso while he was letting dogs out of the trunk of a car while on a hunting trip with his brother on January 21, the regional branch of the Investigative Committee said.

"The trigger was presumably activated" when "the dogs jumped on the man" after he opened the trunk, it said in a statement.

The hunter died on the way to the hospital, it said.

The statement said investigators were still looking into the circumstances of the hunter's death.

According to regional news site Region64, one of two dogs that were in the car stepped on the trigger of the hunting rifle, which it said had its butt in the ground at the time.

Region64 did not identify the source if its information and made no mention of the victim's brother.